Clean up cc.RegisterRequiredBuildComponentsForTest()

Changes this function so it only registers components from the cc
package by pushing the call to genrule.RegisterGenruleBuildComponents()
down into those packages whose tests need it.

This will make it easier to migrate cc package tests to test fixtures
as the RegisterRequiredBuildComponentsForTest() no longer overlaps with
preparers from the genrule packages.

Bug: 181070625
Test: m nothing
Change-Id: Ic00c7e480dc738d7a88d038aca6ab95a1502a24a

java/java_test.go

@@ -25,6 +25,7 @@ import (
 	"strings"
 	"testing"
 
+	"android/soong/genrule"
 	"github.com/google/blueprint/proptools"
 
 	"android/soong/android"
@@ -79,6 +80,8 @@ func testContext(config android.Config) *android.TestContext {
 
 	android.RegisterPrebuiltMutators(ctx)
 
+	genrule.RegisterGenruleBuildComponents(ctx)
+
 	// Register module types and mutators from cc needed for JNI testing
 	cc.RegisterRequiredBuildComponentsForTest(ctx)